Conventionally, industry fields including nondestructive inspection and a medical field including medical check-ups, X-ray diagnosis apparatuses have been widely in use in which a target region or an object is irradiated with radiation (representatively, an X-ray) to detect intensity distribution of radiation having transmitted through the target region or object, yielding an image of the target region or object.
Further, in recent years, ablation procedures have been developed as methods of radical cure in therapies for arrhythmia. In the ablation procedure, confirming electrical conduction and confirming risk reduction are indispensable, and fluoroscopy/radiography continues for a long-time. As a result, the amounts of exposure on an operator and a patient become large. In view of this, techniques of partial fluoroscopy (Spot fluoroscopy) have been developed as a measure to reduce exposure during the fluoroscopy. It is extremely effective to utilize the partial fluoroscopy during the practice of the ablation procedure.
The partial fluoroscopy is a technique of performing fluoroscopy within a limited X-ray irradiation field by limiting the X-ray irradiation field during the fluoroscopy. The technique of the partial fluoroscopy narrows down an X-ray irradiation field for partial fluoroscopy, which is a field required for performing the fluoroscopy in an LIH (last image hold) image as a static image, and displays an image in such a manner as to superimpose, on a part of the LIH image, the fluoroscopy image as a dynamic image based on the fluoroscopy. The partial fluoroscopy is of use for, in particular, intervention of lower limbs, heart, and head part. The partial fluoroscopy can realize exposure reduction by approximately 80% by being used in combination with other low radiation dose techniques.
FIG. 12 is a diagram for explaining a first example of the partial fluoroscopy of conventional techniques.
FIG. 12 shows four X-ray irradiation fields F31-F34, and four images I31-I34 respectively corresponding thereto. Each of the X-ray irradiation fields F31-F34 includes a portion of interest P of the object. Images I31, I32, and I34 are superimposed images displayed during the partial fluoroscopy, in which a partial fluoroscopy image R is superimposed on a part of an LIH image L. The LIH image L in the superimposed image I31 is an image upon setting an X-ray irradiation field Ff for partial fluoroscopy; in other words, an image before change of relative positions of the object and an X-ray detection device.
Before the change of the relative positions of the object and the X-ray detection device, the content within an X-ray irradiation field Fs for radiography in the X-ray irradiation field F31, and the content of the LIH image L in the superimposed image I31 approximately agree with one another. Further, before the change of the relative positions of the object and the X-ray detection device, the content within the X-ray irradiation field Ff for partial fluoroscopy in the X-ray irradiation field F31 and the content of the partial fluoroscopy image R in the superimposed image I31 approximately agree with one another.
Here, there is a case where the relative positions of the object and the X-ray detection device are changed with the superimposed image I31 being displayed during the partial fluoroscopy. For example, in a case where the X-ray detection device is slid in a horizontal direction during the partial fluoroscopy, the X-ray irradiation field Fs for radiography and the X-ray irradiation field Ff for partial fluoroscopy are changed from as shown in X-ray irradiation field F31 to as shown in the X-ray irradiation field F32. Then, the superimposed image I32 is displayed. Here, in the superimposed image I32, the partial fluoroscopy image R in which the relative positions of the object and the X-ray detection device have been changed is superimposed on the LIH image L before the change of the relative positions of the object and the X-ray detection device.
According to the conventional technique shown in FIG. 12, in a case where the X-ray detection device is slid in the horizontal direction with the superimposed image I31 being displayed during the partial fluoroscopy, there is a case where, as shown in X-ray irradiation field F32, the portion of interest P comes out of the X-ray irradiation field Ff for partial fluoroscopy. In this case, the partial fluoroscopy is interrupted and the LIH radiography is again performed in the X-ray irradiation field Fs for radiography shown in the X-ray irradiation field F33, and an LIH image I33 is generated and displayed. When an operator such as operators of the fluoroscopy and radiography again sets the X-ray irradiation field Ff for partial fluoroscopy as shown in the X-ray irradiation field F34, the superimposed image I34 in which the partial fluoroscopy image R is superimposed on a part of the LIH image I33 is generated and displayed.
FIG. 13 is a diagram for explaining a second example of the partial fluoroscopy of the conventional techniques.
FIG. 13 shows two X-ray irradiation fields F31, F35 and two images I31, I35 respectively corresponding thereto. Each of the X-ray irradiation fields F31, F35 includes the portion of interest P of the object. The images I31, I35 are superimposed images in which the partial fluoroscopy image R is superimposed on a part (or whole) of the LIH image L displayed during partial fluoroscopy. The X-ray irradiation field F31 and the superimposed image I31 are equivalent to those shown in FIG. 12.
According to the conventional technique shown in FIG. 13, in a case where the X-ray detection device is slid in the horizontal direction with the superimposed image I31 being displayed during partial fluoroscopy, when the operator stops down an aperture, the X-ray irradiation field Fs for radiography and the X-ray irradiation field Ff for partial fluoroscopy are changed from as shown in the X-ray irradiation field F31 to as shown in the X-ray irradiation field F35. In other words, a movable aperture device has to be back to the normal fluoroscopy position (full-open position of the aperture blade). Then, the superimposed image I35 is displayed.